Applying the Physique Modifier

Adjusting the Biped to the Model

Character Animation without Biped

 

Autodesk 3ds Max Tutorials > Character Animation Tutorials > Adjusting the Biped to the Model > 

Adjusting Envelopes

The bulk of the work in Physique consists of adjusting the size and overlap of envelopes to fine-tune mesh behavior as the character moves.

For the best results, each area of the mesh requires some attention.

• Each envelope should encompass its surrounding vertices
• Hip and shoulder areas must be adjusted for smooth deformation when the biped walks or stretches
• The head requires a rigid envelope for minimal deformation

As you adjust the envelopes, inspect the mesh from various angles. A test animation will also reveal different flaws in the mesh as the biped posture changes.

Set up for this lesson:

1. Load the file my_wilson_physique.max that you created in the lesson Applying the Physique Modifier . Alternately, you can load the file envelopes_wilson_start.max from the program disc.

   

   This scene contains the character Wilson and a posed biped. MeshSmooth has been removed from the character for the time being. Physique has been applied to the model, but the envelopes haven't been adjusted.

   The biped isn't needed for envelope adjustment, so you can hide it for now.

2. Select the Wilson Mesh Body object.
3. Open the Modify panel.
4. In the Physique Level Of Detail rollout, turn on Hide Attached Nodes.

   The biped is hidden, and you have a better view of the mesh.

   TipTurning on Hide Attached Nodes has the same effect as hiding the biped with the controls on the Display panel.
5. Scrub the time slider to frame 10.

   The biped is animated very simply, just enough to show you the main problem areas. The problems with the mesh are:

   • The sleeves don't go with the upper arm
   • The pant legs don't go with the legs as they split
   • The hips do not deform smoothly

   If you're using scene you created with the last two lessons, it's possible that your biped pose differs slightly from the file included on the CD, producing different problems with the hands, fingers, legs, or feet.

   In this lesson, you'll learn to fix the first two problems listed above. You can apply the same principles to other body parts, such as fingers and toes.

   TipTo get a better look at the envelopes and vertices as they change shape, change the Perspective view to a User view and turn on Edged Faces.

Adjust the arm envelopes:

1. In the Front viewport, zoom in on the upper body. The time slider should be at frame 10.
2. Go to the Modify panel.
3. Expand the Physique modifier listing on the stack, and choose the Envelope sub-object.

   The links in the body turn yellow.

4. Click the link for the left upper arm.

   

   Two envelopes appear around the arm link. The vertices inside the envelopes are influenced by the bone. The inner red envelope indicates the area of most influence. The link's influence decreases until it reaches the purple outer envelope. Vertices outside the envelopes are not affected at all by the bone.

   Vertices affected by the currently selected envelope turn various colors to show they are influenced by the envelope.

   The radius of each envelope can be changed with the Radial Scale parameter. Increasing the radius enlarges the envelope to encompass more vertices, increasing the number of vertices affected by the bone.

   TipTo see the envelopes' influence in color in a shaded viewport, turn on the Shaded option in the Blending Envelopes rollout > Display group.
5. In the Blending Envelopes rollout > Envelope Parameters group, increase the Radial Scale parameter until all the vertices in the sleeve pop into place.

   

   To make the other arm's envelope the same, you can copy and paste the envelope settings.

6. In the Edit Commands group, click Copy.
7. Select the right upper arm link and click Paste.

   The sleeve pops into place for the opposite arm.

   

   NoteIt is possible that the right arm envelope's Radial Scale will have to be increased slightly to encompass the sleeve on that arm. Even with a symmetrical model, there can be very slight differences between the biped pose on each side, causing differences in the initial envelope size and placement.

Adjust the leg envelopes:

The envelopes for the lower legs don't fully encompass the entire pant leg near the ankle.

1. Select lower right leg link, and increase the Radial Scale.

   When you increase the Radial Scale enough to encompass the entire pant leg, the outer envelope includes some of the vertices on the other leg. You will solve this problem my moving control points.

   The process of moving control points is easier if you put the character back into its figure pose.

2. In the Display group, turn on Initial Skeletal Pose.

   The character jumps back to its figure pose.

3. In the Blending Envelopes rollout > Selection Level group, click the Control Point button.

   Control points appear on each envelope.

   

4. In the Front viewport, select the control points on the side of the envelope that overlaps the left leg, and move them to the left until the envelopes no longer affect the left leg's vertices.

   

5. In the Blending Envelopes rollout > Selection Level group, click the Link button.
6. Select the lower left leg link. Increase its Radial Scale so the envelopes encompass the entire left pant leg.
7. Click Control Point.

   Control points appear on each envelope.

8. Adjust the control points as you did before, so the lower left leg envelopes don't affect the lower right leg's vertices.

Adjust foot envelopes:

1. Turn off Initial Skeletal Pose.
2. In the Blending Envelopes rollout > Selection Level group, click the Link button.
3. Select one of the foot links, and increase the Radial Scale until any parts of the foot that were sticking out are now following along with the foot bone.
4. Copy and paste the envelope settings to the other foot, or adjust them manually.

Fine-tune the ankle area:

1. Click the Link button, then click the calf link on the left leg.

   

   In looking at the pose on frame 10, you can see that parts of the shoe are affected by the calf link, causing spikes to appear on the shoe. You'll fix this problem by adjusting the Child Overlap parameter. This value changes the length of the envelopes in the direction of the child link. In this case, the foot link is the child of the calf link.

2. In the Envelope Parameters group, decrease the Child Overlap setting until the calf envelope no longer affects the vertices at the back of the heel.

   

   NoteThe Parent Overlap parameter works in the opposite direction, increasing or decreasing the length of the envelopes in the direction of the parent link.
3. Copy and paste the envelope settings to the opposite calf link.

   Although the hips are not deforming correctly just yet, the arms and legs should now deform properly without vertices being left behind or making unsightly spikes. If any problems remain, fix them by working with the Radial Scale, Parent Overlap, and Child Overlap parameters.

Assign a rigid envelope to the head:

The head is not expected to deform when the biped is animated. To keep it from deforming, you'll assign rigid vertices to it.

1. Select the character's head mesh, Wilson Mesh Head.
   NoteBecause the Physique modifier is instanced on both the mesh and head, it doesn't matter whether the head, the mesh, or both objects are selected when you adjust the head envelopes. Any changes to envelopes will take place on both objects regardless of the current selection. You select the head at this time only because it will be easier to see how vertices are affected when you change the envelopes.
2. Access the Envelope sub-object level for the Physique modifier.
3. Click the head link to select it.
4. In the Active Blending group, turn off Deformable and turn on Rigid.

   Vertices on the head turn green to indicate they are rigid.

5. Adjust the outer envelope so it encompasses the head and a little of the neck, but no more.

   

Save your work:

• Save your scene as my_wilson_envelopes.max.

  A scene with adjusted envelopes can be found in the file envelopes_wilson_complete.max.